A drip cap is a feature on the exterior of a window, positioned on peak of the window. It extends out and is intended to channel water out from the window; water follows the contour of the drip cap, and then melts the outer edge.
Chris Hill
The drip cap inside this case is only an elongated bit of flashing which is bent downward.
Burke in Riverhead Building Supply
Drip caps can be incorporated into window architecture.
Camber Construction
The drip cap here is finished expertly and is barely noticeable.